Anode



Patented Feb. 1, 1944 ANODE Charles L. Mantel], Manhassett, N. Y., assignor to Electro Manganese Corporation,

Knoxville,

Tenn., a corporation of Delaware No Drawing. Application January 16, 1043,

. Serial No. 472,619

1 Claim.

This invention relates to anodes adapted particularly for use in the electrowinning of manganese.

In this art lead anodes hav been used but their use is attended with the great disadvantage that large quantities of manganese dioxide are formed at the anode. Fink'and Kolodney U. S. Patent 2,320,773, June 1, 1943, have disclosed that by using alloys, the, constituents of which comprise lead, tin, and antimony, or lead, tin, antimony and cobalt (or lead, tin, antimony, cobalt and silver). that the formation of manganese dioxide can be repressed. This is due to the formation of a coating which catalyzes the formation of oxygen and minimizes the formation of manganese dioxide. The use of such compositions constitutes a distinct improvement in the art. However, suppression of manganese dioxide formation is not the only property which is desirable in an anode. It is desirable that the anode have a long life and be substantially insoluble. An anode which operates satisfactorily only for a short time represents an economic loss.

It is an object of this invention to devise a stable anodewhich has a long life and substantially complete insolubility in addition to the property of suppressing manganese dioxide formation.

It has been discovered that the cause of deterioration is loss of certain constituents, more particularly cobalt and tin, this loss signifying the functioning of the anode, to the extent of the loss, as a soluble anode. It has been further discovered that the loss of these constituents by solution in the electrolyte seriously impairs not only the structure of the anode but also the functioning of the catalytic coating thereon. In the use of anodes containing lead, tin, antimony and cobalt, an adherent film or coating forms on the anode surface, this coating being a complex of certain oxides including the oxides of jlead, tin. cobalt and antimony. This coating performs a valuable catalytic function in accelerating oxygen evolution and minimizing manganese dioxide formation. The desirable properties of the anode depend at least to a large extent upon-maintenance of this coating without rupture. When during use there is a loss of tin or cobalt this coating is disturbed or ruptured and its cataltyic activity in suppressing manganese dioxide forma- 7 tion greatly-impaired.

It has been further discovered that stability of the anode depends upon the use of an anode containing certain maximum critical percentages of cobalt and tin. If the proportions of these elements materially exceed these critical values, in stability upon electrolysis results, accompanied by impairment of the anode structure as well as impairment of the desired functioning of the catalytic coating. For tin the maximum is about 25 Q about 0.02 percent and the tin from about 25 percent to about 20 percent. The chief function of the antimony is to act as a strengthening component and. the range of th proportion of antimony may be froma maximum of about 6 percent to a minimum of about 4 percent. The balance of the composition is for the most part lead, although small amounts of elements normally associated with lead are not precluded, as for example silver.

This invention, therefore, involves the discovery that by limiting the maximum proportion of tin and cobalt, loss of those components during electrolysis is prevented, impairment of the structure and functioning of the anode and its catalytic coating is prevented and a stable anode obtained.

In accordance with the present invention,

In view of the tendency of cobalt to oxidize,

care should be taken to avoid the formation of oxides thereof. It will be found that an anode of this composition is stable and not only has this composition as manufactured but also substantially maintains the above composition during use. Such an anode has been found to have a life reatly exceeding that of an anode having proportions of cobalt, tin and antimony substantially exceeding the critical values above set forth. It will also be found that this stable anode upon use develops a coating which is an oxide complex without limiting the generality thereof, a solid plate or sheet, a perforated sheet, agrid, bars suspended from a horizontal support, and a coating or cladding on a core of other conductive material.

What is claimed is:

An anode for manganese electrowinning hav-' ing the following composition:

Percent by weight Cobalt 0.02to 0.04 Tin 20 12025 Antimony 4 to '6 Balance Principally lead oaaanas L. MANTELL. 

